What I love is this idea of a wardrobe,” says Phoebe Philo, “the idea that we’re establishing certain signatures and updating them, that a change in colour or fabric is enough. I do think the world doesn’t need many more frivolous bits and bobs that end up left in cupboards or landfills.”

She is talking about Celine, the French fashion label she took over in 2008 in a blaze of publicity, and transformed into a global phenomenon almost overnight. Until Philo’s arrival, Celine had been floundering. Under Michael Kors, who stepped down in 2004, it was beloved by the monied New York professional. However, despite the brand’s longevity it was founded in 1945 by Celine Vipiana it lacked a heritage to rival the more well known French fashion houses. There was no trademark tuxedo or pussy bow blouse to think of, for example, nor anything remotely as famous as Dior’s New Look line skirt or Chanel’s boucle wool suit.

“Some of the brands I respect most in the world have that core,” Philo continues, “so I’m proud that people are now coming back and asking for the same thing.”

With that in mind, and just a little over two years after Philo’s arrival, the Celine look is already instantly identifiable. There’s the collarless white shirt with ultra long cuffs designed to be worn with tails trailing behind; the fluid, wide legged trousers; the sleeveless dress that stands away from the body as opposed to clinging to its curves; the crepe jumpsuit, and several highly covetable bags.

“There are elements that have become classics to us. They sell really well. The response has been good. Trousers, tailoring, shirts, skirts, ‘category pieces’.

“I hate these kinds of words but they’ve sort of become [she pulls a face] staples .”

It’s safe to say Celine is today the ultimate stealth wealth tag for the intelligent, modern woman to see and be seen in. And more impressive still is the fact that Philo doesn’t rely on anything obviously publicity seeking or high impact. Instead, the appeal of her work lies in its apparent simplicity and unassuming, no frills approach. This is an aesthetic aimed squarely at a discerning, confident customer who would rather not parade obvious fashion credentials and for whom both modesty and discretion are of prime importance. And, for that, it is a breath of fresh air.

The Celine autumn/winter pre collection, which goes on sale this month, is very much a variation on a similar theme. “It’s pretty masculine. That’s how I dress and I think it’s quite liberating for women not to have to be so preoccupied with different silhouettes, with different things,” Philo says.

The powers that be behind the LVMH owned Celine courted Philo for some time and have been unusually flexible where any working arrangements are concerned. Philo’s position is pretty much unique among fashion designers. Celine is based in Paris but she lives and works in London. She has suitably grand, though certainly not ostentatious, offices in a Georgian townhouse in Cavendish Square and the technicians who produce her designs travel from France on a weekly basis to show her any prototypes or work in progress.

Philo insists on a reasonable working day. For the most part she makes sure she’s home to put her children to bed each night she has two by her long time partner and husband, the art gallery owner Max Wigram.

“I have a fantastic team and it’s much easier having children, because that creates a natural limit. If I have a good time with them before they go to sleep, it’s worth everything to me.”

When, in 2006, Philo left Chloe for “personal reasons”, the label was at the height of its success. She arrived there in 1997 as Stella McCartney’s first assistant and when sales were on the floor. She was made creative director in 2001 when the latter went into partnership with the Gucci Group to launch her own label.

It was widely understood that the secret of Chloe’s turnaround had been Philo’s ability to identify what the label’s young customers might like to wear even before they’d realised it for themselves. When she took to the helm, that fact was driven home. Boyish tailoring and sweetly flirtatious voluminous tunics, the money spinning Paddington bag with its ultra cute and chunky padlock, equally clunky wooden heeled shoes, butterfly pendants and more, sold like the proverbial hot cakes. Philo resigned in a genuine and openly expressed bid for a well earned break.

Nonetheless, she found herself in the fortuitous position of becoming hotter property still as speculation mounted over what Phoebe might do next.

Visitors to Celine’s London premises are greeted by a seascape by French photographer Marine Hugonnier and a twinkling Tim Noble and Sue Webster light installation that reads, “forever”. Philo’s office, on the second floor, is dominated by huge windows and and a very high ceiling.

The designer is wearing a masculine white shirt and cropped black trousers, men’s shoes which appear to be several sizes too big for her, and a shrunken, black leather biker jacket, with articulated quilting at the elbows that she says she bought in Japan. “I wear it all the time,” she laughs. “It’s taken on my body shape.” Her sandy blonde hair is pulled back from her classically beautiful face, her pale, blue eyes are huge, her cheekbones chiselled and her skin is as nature intended entirely make up free. She says she looks “a bit butch, I suppose”.

Philo, it has been said before on numerous occasions, is the best possible advocate of her own designs. Also oft repeated: she is clearly in possession of the best possible taste. In the past, she has been described as aloof and even cold, but that is unfair. Philo is wary, clearly, but disarmingly straight talking and not one to suffer fools. Given that interviews with the designer are extremely rare, it’s safe to assume she’s ill at ease in the presence of journalists. Certainly, her reluctance to talk about her private life is palpable.

“I’m not like that on purpose. It’s just about my comfort zone,” she says, not unreasonably.

Philo doesn’t tweet, blog or communicate via Facebook. When she shows her collections, her backstage area isn’t open to the media.

In an age where fashion designers are expected to step out on the red carpet alongside the people they are required to dress at every given opportunity, Philo refuses to play that game. In light of the media circus that the fashion industry has become, that is refreshing as ultimately forward thinking as her clothes.

“Do you hate being interviewed?”

“I just feel it’s really unnecessary.”

“But it’s a requirement of the job?”

“It is. But I think that the clothes say it all much better than I can. I always find it strange after a show when everybody comes backstage and says: ‘What was it all about’? It’s like: ‘You’ve just seen it. What do you mean?’ My instinct is to say: ‘What did you think? What did you get from it?’

“To me, the show is quite a complete story. There’s nothing more for me to say and, anyway, it doesn’t matter what it was meant to say. It’s out there. It can be whatever anyone watching it thought it was, surely.”

To sum up, Philo is deliberately and uncompromisingly media unfriendly and, though that might frustrate those queuing up to gain access to her, it has served her well. Despite the zeitgeist, history has proved that leaving at least something to the imagination has never done anyone any harm.

“I do like the idea of women not showing too much,” she says, “of them being quite reserved in a way, and quite covered,” and she might just as easily be talking about herself as a person as her designs for Celine.